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The Selective α1 Antagonist Tamsulosin Alters ECM Distributions and Cellular Metabolic Functions of ARPE 19 Cells in a Concentration-Dependent Manner. BIOENGINEERING (BASEL, SWITZERLAND) 2022; 9:bioengineering9100556. [PMID: 36290524 PMCID: PMC9598783 DOI: 10.3390/bioengineering9100556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/27/2022] [Revised: 09/27/2022] [Accepted: 10/11/2022] [Indexed: 11/05/2022]
Abstract
The purpose of the present study was to examine the effect of the selective α1 antagonist tamsulosin (TAM) on human retinal pigment epithelium cells, ARPE 19. Two-dimension (2D) and three-dimension (3D) cultured ARPE 19 cells were used in the following characterizations: (1) ultrastructure by scanning electron microscopy (SEM) (2D); (2) barrier functions by transepithelial electrical resistance (TEER) measurements, and FITC-dextran permeability (2D); (3) real time cellular metabolisms by Seahorse Bioanalyzer (2D); (4) physical properties, size and stiffness measurements (3D); and (5) expression of extracellular matrix (ECM) proteins, including collagen1 (COL1), COL4, COL6 and fibronectin (FN) by qPCR and immunohistochemistry (2D and 3D). TAM induced significant effects including: (1) alteration of the localization of the ECM deposits; (2) increase and decrease of the TEER values and FITC-dextran permeability, respectively; (3) energy shift from glycolysis into mitochondrial oxidative phosphorylation (OXPHOS); (4) large and stiffened 3D spheroids; and (5) down-regulations of the mRNA expressions and immune labeling of most ECM proteins in a concentration-dependent manner. However, in some ECM proteins, COL1 and COL6, their immunolabeling intensities were increased at the lowest concentration (1 μM) of TAM. Such a discrepancy between the gene expressions and immunolabeling of ECM proteins may support alterations of ECM localizations as observed by SEM. The findings reported herein indicate that the selective α1 antagonist, TAM, significantly influenced ECM production and distribution as well as cellular metabolism levels in a concentration-dependent manner.
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Damian DB, Ghiță AM, Istrate S, Coman IC. Experimental research in rats on the reactivity of new corneal blood vessels to adrenaline. Rom J Ophthalmol 2021; 65:64-69. [PMID: 33817436 PMCID: PMC7995500 DOI: 10.22336/rjo.2021.12] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/04/2021] [Indexed: 11/18/2022] Open
Abstract
Aim: The purpose of this experimental study was to evaluate the existence of adrenergic receptors in ketamine-induced corneal blood vessels in rat pups. Methods: The study of corneal neovascularization motricity was performed on 45-day-old Wistar rats in which, starting from the 15th day of life, corneal blood vessels were obtained by injecting intraperitoneal ketamine at a dose of 150 mg/ kg body weight, a total of 5 successive doses. The examination of the neovascularization was done with the help of a Nikon stereomicroscope connected to a video camera and a computer, the total magnification being 400X. The reactivity of the new corneal blood vessels to the administration in conjunctival instillations of a 1.5 mmol/L adrenaline solution was tested. The parameters followed were represented by variations in the caliber of corneal blood vessels. The data were analyzed using Microsoft Office Excel. Results: Administration of distilled water did not produce statistically significant changes in corneal blood vessels, while adrenaline produced a statistically significant constriction of vascular diameter (p=0.01 at T9, p=0.004 at T10, p=0.019 at time T11 of examinations). Conclusions: The results showed that adrenaline produces vasoconstriction in the new corneal blood vessels, which allows us to assume that they contain α-adrenergic receptors. However, we cannot say that corneal pathological vessels do not contain β2-type adrenergic receptors, because the effect of adrenaline may be an algebraic sum between vasoconstriction produced by stimulating α-adrenergic receptors and vasodilation produced by stimulating β2-adrenergic receptors, but in which the vasodilating effect may be masked by the vasoconstrictor effect given by a higher density of α-adrenergic receptors. Abbreviations: A= adrenaline, DNM = non-measurable diameter, NA= noradrenaline, Std.Er.= Standard error.
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Affiliation(s)
- Daniela Bianca Damian
- Department of Ophthalmology, “Dr. Alexandru Popescu” Military Emergency Hospital Focșani, Focșani, Vrancea, Romania
| | - Aurelian Mihai Ghiță
- Department of Physiology, “Carol Davila” University of Medicine and Pharmacy, Bucharest, Romania
| | - Sânziana Istrate
- Department of Ophthalmology, “Carol Davila” University of Medicine and Pharmacy, Bucharest, Romania
| | - Ioana Cristina Coman
- Department of Ophthalmology, “Carol Davila” University of Medicine and Pharmacy, Bucharest, Romania
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Klyce SD. 12. Endothelial pump and barrier function. Exp Eye Res 2020; 198:108068. [PMID: 32663497 DOI: 10.1016/j.exer.2020.108068] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 05/11/2020] [Accepted: 05/12/2020] [Indexed: 10/23/2022]
Abstract
The mammalian cornea maintains its thickness and transparency primarily by the activity of a fluid pump located in the endothelial cell layer. The accepted concept, the "pump-leak" theory, holds that the active transport of solute from the stroma to the aqueous humor leads to a steady state osmotic pressure gradient across the endothelium that balances the imbibition pressure created by the hydrophilic proteoglycans in the stromal ground substance. The details of this process are controversial and some of the classical in vitro studies aimed to explore the fluid pump using low temperature to challenge the regulatory behavior cannot be duplicated in vivo. The activity of sensory or sympathetic innervation may play a role in this low temperature tolerance. Asymmetry in endothelial cell volume regulation could be the basis for the fluid pump.
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Affiliation(s)
- Stephen D Klyce
- Ophthalmology, Icahn School of Medicine at Mount Sinai 5 North Court Port, Washington, NY, 11050, United States.
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Musayeva A, Manicam C, Steege A, Brochhausen C, Straub BK, Bell K, Pfeiffer N, Gericke A. Role of α 1-adrenoceptor subtypes on corneal epithelial thickness and cell proliferation in mice. Am J Physiol Cell Physiol 2018; 315:C757-C765. [PMID: 30257104 DOI: 10.1152/ajpcell.00314.2018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Adrenergic stimuli are important for corneal epithelial structure and healing. The purpose of the present study was to examine the hypothesis that the lack of a single α1-adrenoceptor (α1-AR) subtype affects corneal epithelial thickness and cell proliferation. Expression levels of α1-AR mRNA were determined in mouse cornea using real-time PCR. In mice devoid of one of the three α1-AR subtypes (α1A-AR-/-, α1B-AR-/-, α1D-AR-/-) and in wild-type controls, thickness of individual corneal layers, the number of epithelial cell layers, and average epithelial cell size were determined in cryosections. Endothelial cell density and morphology were calculated in corneal explants, and epithelial cell proliferation rate was determined with immunofluorescence microscopy. Moreover, the ultrastructure of the corneal epithelium was examined by transmission electron microscopy. Messenger RNA for all three α1-AR subtypes was expressed in whole cornea and in corneal epithelium from wild-type mice with a rank order of abundance of α1A ≥ α1B > α1D. In contrast, no α1-AR mRNA was detected in the stroma, and only α1B-AR mRNA was found in the Descemet endothelial complex. Remarkably, corneal epithelial thickness and mean epithelial cell size were reduced in α1A-AR-/- mice. Our findings suggest that the α1A-AR exerts growth effects in mouse corneal epithelial cells.
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Affiliation(s)
- Aytan Musayeva
- Department of Ophthalmology, University Medical Center, Johannes Gutenberg University Mainz , Mainz , Germany
| | - Caroline Manicam
- Department of Ophthalmology, University Medical Center, Johannes Gutenberg University Mainz , Mainz , Germany
| | - Andreas Steege
- Department of Internal Medicine II, University Medical Center Regensburg , Regensburg , Germany
| | - Christoph Brochhausen
- Institute of Pathology, University Medical Center, Johannes Gutenberg University Mainz , Mainz , Germany.,Institute of Pathology, University Medical Center Regensburg , Regensburg , Germany
| | - Beate K Straub
- Institute of Pathology, University Medical Center, Johannes Gutenberg University Mainz , Mainz , Germany
| | - Katharina Bell
- Department of Ophthalmology, University Medical Center, Johannes Gutenberg University Mainz , Mainz , Germany
| | - Norbert Pfeiffer
- Department of Ophthalmology, University Medical Center, Johannes Gutenberg University Mainz , Mainz , Germany
| | - Adrian Gericke
- Department of Ophthalmology, University Medical Center, Johannes Gutenberg University Mainz , Mainz , Germany
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Authors' reply to comments to: Anterior segment morphologic changes related to α-1 adrenergic receptor antagonists use. Eur J Ophthalmol 2016; 26:e61. [PMID: 26833228 DOI: 10.5301/ejo.5000753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/08/2016] [Indexed: 11/20/2022]
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Grueb M, Mielke J, Rohrbach JM, Schlote T. Effect of Brimonidine on Corneal Thickness. J Ocul Pharmacol Ther 2011; 27:503-9. [DOI: 10.1089/jop.2010.0198] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Matthias Grueb
- Department of Ophthalmology, University of Tuebingen, Tuebingen, Germany
- Private Practice, Augenarztpraxis Breisach, Breisach am Rhein, Germany
| | | | | | - Torsten Schlote
- Department of Ophthalmology, University of Tuebingen, Tuebingen, Germany
- Day Clinic Ambimed, Basel, Switzerland
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Grueb M, Wallenfels-Thilo B, Denk O, Mielke J, Reinthal E, Rohrbach JM, Bartz-Schmidt KU. Monoamine receptors in human corneal epithelium and endothelium. ACTA ACUST UNITED AC 2006; 84:110-5. [PMID: 16445449 DOI: 10.1111/j.1600-0420.2005.00551.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
PURPOSE Monoamine receptors are found throughout the body. Reports about the presence of monoamine receptors in the human cornea are inconsistent. METHODS Immunohistochemistry, immunofluorescence and immunoblotting were used to localize monoamine receptor sites on human corneal epithelium and endothelium. RESULTS Antibodies to alpha-1, beta-1 and beta-2 adrenergic receptors and to D1-like and 5HT-7 receptors were bound in corneal epithelium. Antibodies to alpha-1, alpha-2A, beta-1 and beta-2 adrenergic receptors and to 5HT-7 receptors were bound in corneal endothelium. CONCLUSIONS Our data demonstrate the presence of several monoamine receptors in the human cornea. These receptors may play a role in the regulation of fluid transport or corneal homeostasis.
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Affiliation(s)
- Matthias Grueb
- Department of Ophthalmology, University of Tuebingen, Tuebingen, Germany.
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Loh RS, Hardten DR. Noninflammatory flap edema after laser in situ keratomileusis associated with asymmetrical preoperative corneal pachymetry. J Cataract Refract Surg 2005; 31:922-9. [PMID: 15975457 DOI: 10.1016/j.jcrs.2004.08.058] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/24/2004] [Indexed: 12/01/2022]
Abstract
PURPOSE To report persistent unilateral flap edema following laser in situ keratomileusis (LASIK) in patients with asymmetrical central corneal thickness. SETTING Minnesota Eye Consultants, Minneapolis, Minnesota. METHODS Retrospective, noncomparative interventional case series. RESULTS We examined 6 eyes of 3 patients with asymmetrical preoperative pachymetry who developed persistent unilateral flap edema after uneventful myopic LASIK in the eye with thicker preoperative pachymetry. All cases had asymmetrical preoperative pachymetry with flap edema developing in the eye with higher preoperative mean central corneal thickness (CCT) values, preoperative mean CCT subject eye 622 microm (range 556-664 microm) versus fellow eye 583 microm (range 510-621 microm). There was no associated ocular inflammation or rise in intraocular pressure. Significant flap edema resolved on a combination treatment of topical steroid and hypertonic saline. CONCLUSIONS Laser in situ keratomileusis can cause temporary endothelial cell dysfunction or stress, which manifests as temporary flap edema and subclinical corneal thickening. The edema appears to be limited to the actual flap and there was no loss of epithelial integrity in these eyes and no clinically noticeable interface fluid. This new clinical entity appears to occur in patients with asymmetrical preoperative corneal pachymetry and is associated with postoperative specular microscopy abnormalities. In cases with unexplained asymmetrical corneal thickness, preoperative evaluation should include specular microscopy to evaluate for risk features that may increase the chances of a slower postoperative recovery.
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Affiliation(s)
- Raymond S Loh
- Minnesota Eye Consultants, Minneapolis, Minnesota, USA
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Passmore JC, Rowell PP, Joshua IG, Porter JP, Patel DH, Falcone JC. Alpha 1 adrenergic receptor control of renal blood vessels during aging. Can J Physiol Pharmacol 2005; 83:335-42. [PMID: 15877108 DOI: 10.1139/y05-015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Aging humans and rats have a reduced renal vascular constriction response to stress, change in posture, or exercise. In this study, renal interlobar arteries from 9- (intermediate age) to 15-month-old (aging) male Wistar rats constricted less to alpha-adrenergic agonists than those of 4-month-old (young adult) rats. The reduced contraction to A61603 (alpha 1 A agonist) was similar to that to norepinephrine and phenylephrine. Therefore, it appears that the reduction in constriction is primarily related to alpha 1 A receptor stimulation. GeneChip microarray hybridization analysis of the interlobar arteries with the RAE 230A GeneChip indicated that there were no significant differences in gene expression for alpha 1 A/C, 1B, or 1D receptors between 4-month-old (young adult) and 1-year-old (aging) male Wistar rats. Competitive binding experiments (prazosin) revealed that maximal binding (Bmax, fmol/mg protein) of the alpha 1 receptors of interlobar arteries was reduced 25% by 10 months of age and 50% by 18+ months of age. Alpha 1 receptor-induced arterial constriction and prazosin binding were both down-regulated. The loss of receptor-initiated constriction likely includes down-regulation of maximum agonist binding by alpha 1 adrenergic receptors.Key words: kidney, stress, blood flow, male vs. female, GeneChip array, prazosin.
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Affiliation(s)
- John C Passmore
- Department of Physiology and Biophysics, School of Medicine, University of Louisville, KY 40292, USA.
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Cavallotti C, Pescosolido N, Artico M, Pacella E, Cavallotti D. Occurrence of catecholaminergic nerve fibers in the human uveoscleral tissue in conditions of normal and raised intraocular pressure. Int Ophthalmol 2003; 24:133-9. [PMID: 12498509 DOI: 10.1023/a:1021173115883] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The distribution of catecholaminergic nerve fibers (CNF) in human uveoscleral tissue was studied in six human eyes with normal intraocular pressure and in five eyes with increased pressure. The eyes with increased pressure had no visual field alterations and the patients did not have any glaucoma-related optic neuropathies. The amount of norepinephrine in these structures was also analysed. Catecholaminergic nerve fibers were detected by means of fluorescence microscopy and were counted using the quantitative analysis of images. Our results demonstrate that the occurrence of catecholaminergic nerve fibers (expressed in Conventional Units = C.U.) in human uveoscleral tissue is 15.4 +/- 1.6 C.U. in eyes with normal intraocular pressure. In eyes with increased intraocular pressure, these values were 12.2 +/- 1.2 C.U. Moreover, the amount of norepinephrine in tissue homogenates of the same eyes was evaluated and found to be 21.7 +/- 1.3 microg/gr tissue fresh weight of the human uveoscleral tissue in eyes with normal intraocular pressure. This value decreased to 18.8 +/- 1.1 microg/gr tissue fresh weight in the same tissue in conditions of raised intraocular pressure. In these experiments, the small number of eyes examined made it difficult to draw general conclusions. However, the role of human uveoscleral tissue was emphasized by the rich catecholaminergic innervation. A decrease of catecholaminergic nerve fibers and norepinephrine occurs when intraocular pressure is elevated. The modifications of these parameters, involved in the sympathetic control of aqueous humor outflow, may support the hypothesis of a possible relevant role for the human uveoscleral tissue in different pathological conditions.
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Affiliation(s)
- C Cavallotti
- Department of Human Anatomy, University La Sapienza, Rome, Italy.
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Suzuki F, Taniguchi T, Nakamura S, Akagi Y, Kubota C, Satoh M, Muramatsu I. Distribution of alpha-1 adrenoceptor subtypes in RNA and protein in rabbit eyes. Br J Pharmacol 2002; 135:600-8. [PMID: 11834607 PMCID: PMC1573172 DOI: 10.1038/sj.bjp.0704503] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
We investigated subtypes of alpha-1 adrenoceptor (AR) in rabbit ocular tissues using reverse transcription-polymerase chain reaction (RT - PCR), in situ hybridization (ISH) and binding studies. Competitive RT - PCR assays specific for the subtypes of alpha-1 AR revealed that the mRNA expression of alpha-1a AR was dominant, and that of each alpha-1b and alpha-1d was less than 10% and 0.5% of total alpha-1 ARs mRNA, respectively, in the iris, ciliary body, choroid and retina. In alpha-1a AR splice isoform-specific RT - PCR assays, we found a distinct proportion of each isoform mRNA in the iris, ciliary body and choroid. The results of the ISH assays for alpha-1a AR subtype showed that hybridization signals were clearly observed in the iris dilator muscle and in the epithelium of the ciliary processes. In binding studies, alpha-1A AR was a dominant subtype in the iris, choroid and retina in contrast to the ciliary body that had more alpha-1B than alpha-1A AR subtype at protein level.
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Affiliation(s)
- Fumiko Suzuki
- Department of Pharmacology, School of Medicine, Fukui Medical University, Matsuoka, Fukui 910-1193 Japan
| | - Takanobu Taniguchi
- Department of Pharmacology, School of Medicine, Fukui Medical University, Matsuoka, Fukui 910-1193 Japan
| | - Seigo Nakamura
- Department of Ophthalmology, School of Medicine, Fukui Medical University, Matsuoka, Fukui 910-1193 Japan
| | - Yoshio Akagi
- Department of Ophthalmology, School of Medicine, Fukui Medical University, Matsuoka, Fukui 910-1193 Japan
| | - Chikara Kubota
- Department of Anatomy, School of Medicine, Fukui Medical University, Matsuoka, Fukui 910-1193 Japan
| | - Makoto Satoh
- Department of Anatomy, School of Medicine, Fukui Medical University, Matsuoka, Fukui 910-1193 Japan
| | - Ikunobu Muramatsu
- Department of Pharmacology, School of Medicine, Fukui Medical University, Matsuoka, Fukui 910-1193 Japan
- Author for correspondence:
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Zamir E, Chowers I, Banin E, Frucht-Pery J. Neurotrophic corneal endothelial failure complicating acute Horner syndrome. Ophthalmology 1999; 106:1692-6. [PMID: 10485536 DOI: 10.1016/s0161-6420(99)90362-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
PURPOSE The authors report the clinical findings of a unique case of rapid corneal endothelial decompensation in association with acute Horner syndrome. STUDY DESIGN Case report and literature review. METHODS The authors followed a 38-year-old woman who developed Horner syndrome after right jugular vein catheterization during cardiac valvular surgery. Shortly after the operation, Horner syndrome accompanied by conjunctival hyperemia and stromal corneal edema developed in the right eye. Over the course of 4 months, the eye became painful, the corneal endothelial cell count dropped precipitously, and the stromal edema worsened, causing a difference of 100 microm in central corneal thickness compared to the unaffected eye. Deep stromal vascularization started at the limbus, resembling interstitial keratitis. RESULTS A 3-week course of topical steroid treatment resulted in a dramatic improvement in the stromal corneal edema and regression of the deep stromal vascularization. Ocular and right hemicranial pain subsided shortly thereafter. CONCLUSION The authors hypothesize that corneal endothelial failure in this unique case may have resulted from traumatic sympathectomy. According to experimental evidence in the reviewed ophthalmologic literature, sympathetic innervation may have a neurotrophic role in the cornea. Corneal pathology similar to the authors' case has been described in hemifacial atrophy (Parry-Robson syndrome), a disorder that is assumed to result from sympathetic denervation and that can be produced in animals by cervical sympathectomy. The authors therefore hypothesize that sympathetic denervation of the cornea may rarely cause endothelial decompensation and corneal edema. To the authors' knowledge, this is the first reported case of corneal endothelial failure in Horner syndrome.
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Affiliation(s)
- E Zamir
- Hadassah University Hospital, Jerusalem, Israel.
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Crawford KM, MacCallum DK, Ernst SA. Agonist-induced Ca2+ mobilization in cultured bovine and human corneal endothelial cells. Curr Eye Res 1993; 12:303-11. [PMID: 8100493 DOI: 10.3109/02713689308999454] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
We investigated the possibility that cultured corneal endothelial cells express receptors that are coupled to the phosphoinositide cycle/intracellular Ca2+ signaling pathway. Agonist-stimulated changes in intracellular calcium ([Ca2+]i) in single bovine and human corneal endothelial cells (BCEC and HCEC, respectively) derived from confluent cultures were measured by microspectrofluorimetry using the Ca(2+)-sensitive probe, fura-2. Total inositol phosphates accumulated during a 30 min incubation in the presence or absence of agonists was determined in Li+ containing medium with cells pre-labelled for 48 hrs with 10 microCi/ml 3H-myoinositol. Histamine (HA), ADP and ATP induced a rapid increase in [Ca2+]i. Subsequently, [Ca2+]i decreased to either a stable, agonist-dependent sustained elevation, or fell back to baseline to begin oscillatory fluctuations. The initial rise in [Ca2+]i was insensitive to removal of extracellular calcium (Ca2+o), whereas the stable elevations in [Ca2+]i and the [Ca2+]i oscillations required Ca2+o. In contrast, bradykinin (BK) and endothelin-1 (ET-1) elicited an initial rise in [Ca2+]i that returned to prestimulatory levels within 2 min despite the continued presence of agonist. The Ca(2+)-mobilizing agonists carbachol, phenylephrine, adenosine and substance P were all ineffective in elevating [Ca2+]i. Histamine-induced Ca2+ mobilization was inhibited by the H1-receptor antagonist triprolidine, but triprolidine had no effect on either BK or ATP stimulation of Ca2+ mobilization. In BCEC, 100 microM HA significantly increased total inositol phosphate accumulation (18.8-fold over unstimulated controls) and was 90% inhibited by 0.5 microM triprolidine. BK and ATP also significantly increased formation of inositol phosphates in BCEC.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- K M Crawford
- Department of Anatomy and Cell Biology, University of Michigan, Ann Arbor 48109-0616
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Walkenbach RJ, Ye GS, Boney F, Dueker DK. Muscarinic cholinoceptors in native and cultured human corneal endothelium. Curr Eye Res 1993; 12:155-62. [PMID: 8449026 DOI: 10.3109/02713689308999483] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Specific and high affinity binding of the potent muscarinic cholinergic antagonist, [3H]quinuclidinylbenzilate ([3H]QNB) was observed using intact native and cultured adult human corneal endothelium (HCE). Specific binding was proportional to radioligand concentration between 0.03 and 5 nM, indicating a maximal binding capacity (Bmax) of 130 fmol of [3H]QNB/mg protein and a dissociation constant (Kd) of 0.3 nM. Atropine competed effectively with [3H]QNB for binding sites; requiring 3 nM to inhibit 50% of the binding of 1 nM [3H]QNB. Carbachol also competed with [3H]QNB at higher concentrations, but nicotine did not affect [3H]QNB binding at levels up to 1 nM. [3H]QNB binding was also observed in cultured cells of adult human, rabbit, and bovine corneal endothelium. Native and cultured HCE were affinity labelled using tritium-labelled propylbenzilylcholine mustard (PBCM). Separation of the proteins in affinity labelled native and cultured tissue by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) showed that only one protein in each preparation, of 60 and 55 kilodaltons (kDa), respectively, was specifically radiolabelled. These data indicate that the corneal endothelium of human and several animal species exhibit muscarinic cholinoceptors.
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